feat: support custom app secret in the setup() call + EVM signTypedData fixes

src/api/setup.ts

@@ -1,6 +1,6 @@
 import { Utils } from '..';
 import { Client } from '../client';
-import { setSaveClient, setLoadClient, saveClient, loadClient } from './state';
+import { loadClient, saveClient, setLoadClient, setSaveClient } from './state';
 import { buildLoadClientFn, buildSaveClientFn, queue } from './utilities';
 
 /**
@@ -15,6 +15,7 @@ type SetupParameters = {
   deviceId: string;
   password: string;
   name: string;
+  appSecret?: Buffer;
   getStoredClient: () => string;
   setStoredClient: (clientData: string | null) => void;
 };
@@ -28,6 +29,7 @@ type SetupParameters = {
  * @param {string} SetupParameters.deviceId - the device id of the client
  * @param {string} SetupParameters.password - the password of the client
  * @param {string} SetupParameters.name - the name of the client
+ * @param {Buffer} SetupParameters.appSecret - if set, this app secret will be used instead of the default one
  * @param {Function} SetupParameters.getStoredClient - a function that returns the stored client data
  * @param {Function} SetupParameters.setStoredClient - a function that stores the client data
  * @returns {Promise<boolean>} - a promise that resolves to a boolean that indicates whether the Client is paired to the application to which it's attempting to connect
@@ -37,6 +39,7 @@ export const setup = async ({
   deviceId,
   password,
   name,
+  appSecret,
   getStoredClient,
   setStoredClient,
 }: SetupParameters): Promise<boolean> => {
@@ -47,7 +50,8 @@ export const setup = async ({
   setLoadClient(buildLoadClientFn(getStoredClient));
 
   if (deviceId && password && name) {
-    const privKey = Utils.generateAppSecret(deviceId, password, name);
+    const privKey =
+      appSecret ?? Utils.generateAppSecret(deviceId, password, name);
     const client = new Client({ deviceId, privKey, name });
     return client.connect(deviceId).then((isPaired) => {
       saveClient(client.getStateData());

src/ethereum.ts

@@ -2,9 +2,9 @@
 // does not have browser (or, by proxy, React-Native) support.
 import { Chain, Common, Hardfork } from '@ethereumjs/common';
 import { TransactionFactory } from '@ethereumjs/tx';
+import { SignTypedDataVersion, TypedDataUtils } from '@metamask/eth-sig-util';
 import BN from 'bignumber.js';
 import cbor from 'borc';
-import { SignTypedDataVersion, TypedDataUtils } from '@metamask/eth-sig-util';
 import { keccak256 } from 'js-sha3';
 import { encode as rlpEncode } from 'rlp';
 import secp256k1 from 'secp256k1';
@@ -76,7 +76,7 @@ const validateEthereumMsgResponse = function (res, req) {
     const digest = prehash ? prehash : encoded;
     const chainId = parseInt(input.payload.domain.chainId, 16);
     // Get recovery param with a `v` value of [27,28] by setting `useEIP155=false`
-    return addRecoveryParam(digest, sig, signer, { chainId });
+    return addRecoveryParam(digest, sig, signer, { chainId, useEIP155: false });
   } else {
     throw new Error('Unsupported protocol');
   }
@@ -853,6 +853,18 @@ function parseEIP712Msg(msg, typeName, types, forJSParser = false) {
   return msg;
 }
 
+class PatchedBN extends BN {
+  // compatibility hack with borc lib which may internally use a different
+  // version of the lib which could then cause internal check for type to
+  // fail, ultimately resulting in incorrect serialization of bignumber instances
+  // passed from outside
+  // this line in borc (instanceof instead of `isBigNumber()` check) seems to be the source of the issue:
+  // https://github.com/dignifiedquire/borc/blob/1bd231963344d8ce2dfb9d9bcf04ea29ff4875de/src/encoder.js#L329
+  encodeCBOR(gen) {
+    return gen._pushBigNumber(gen, this);
+  }
+}
+
 function parseEIP712Item(data, type, forJSParser = false) {
   if (type === 'bytes') {
     // Variable sized bytes need to be buffer type
@@ -900,7 +912,7 @@ function parseEIP712Item(data, type, forJSParser = false) {
     // TODO: Find another cbor lib that is compataible with the firmware's lib in a browser
     // context. This is surprisingly difficult - I tried several libs and only cbor/borc have
     // worked (borc is a supposedly "browser compatible" version of cbor)
-    data = new BN(data);
+    data = new PatchedBN(data);
   } else if (
     ethMsgProtocol.TYPED_DATA.typeCodes[type] &&
     (type.indexOf('uint') > -1 || type.indexOf('int') > -1)
@@ -918,8 +930,9 @@ function parseEIP712Item(data, type, forJSParser = false) {
       // For EIP712 encoding in this module we need strings to represent the numbers
       data = `0x${b.toString('hex')}`;
     } else {
-      // Load into bignumber.js used by cbor lib
-      data = new BN(b.toString('hex'), 16);
+      // Load into patched bignumber.js to bypass potential mismatch with bignumber version used
+      // by borc lib internally
+      data = new PatchedBN(b.toString('hex'), 16);
     }
   } else if (type === 'bool') {
     // Booleans need to be cast to a u8